Process and material properties of HfLaOx prepared by atomic layer deposition

Abstract

The atomic layer deposition (ALD) process of hafnium-lanthanum oxide (HfLa Ox) using La (iPrCp)3 and Hf (NEtMe)4 precursors is described. It has been found that when Hf precursor is introduced, the ALD process of La2 O3 is significantly improved in terms of its deposition rate and self-limiting property. An enhanced deposition rate and good controllability of the composition ratio of HfLa Ox was achieved. The mechanism behind this enhancement is discussed. Using high-resolution X-ray photoelectron spectroscopy, the band structure of HfLa Ox as a function of La percentage is analyzed. It has been found that the energy bandgap (Eg) and conduction and valance band offsets (Δ Ec and Δ Ev) of HfLa Ox change linearly with the La percentage. The Eg changes from 4.92 to 5.67 eV and the Δ Ec from 1.21 to 2.4 eV as the La percentage varies from 0 to 81%. The ALD HfLa Ox dielectric exhibits excellent electrical properties with a low leakage current and a high breakdown field, even after high-temperature anneal up to 1050°C, which makes HfLa Ox a promising candidate for complementary metal oxide semiconductor integrated-circuit application. © 2008 The Electrochemical Society.